Conclusion

Since antiquity we have known that many insects produce sounds, but only during the past 150 years have scientists realized that some insects can hear. Detailed descriptions of ear anatomy, and the behaviors associated with hearing, began in the early 1800s, providing the basis for current developments in the field of insect bioacoustics. Over the past 40 years there have been significant advances in the field: many new ears have been discovered, and previous claims to tympanal hearing (based on morphological studies) have been validated. With the development of new instruments for detecting acoustic signals outside the realm of human perception (e.g., ultrasound, solid-substrate-borne vibrations), and for recording neurophysiological responses to sound, we are now beginning to better appreciate the immense diversity of insect sound receptor organs.

There is still much to learn about insect hearing. We know little, for example, about the chain of physical and bioelectrical events leading to sound reception at the level of the auditory cells or how acoustic sensory responses are integrated at the level of the central nervous system to promote adaptive behaviors. New tympanal ears will no doubt turn up in the years ahead, but perhaps most significantly, future explorations into substrate-vibrational and near-field sound communication are sure to yield exciting insights into how insects communicate acoustically.